1. Field of the Ivention
This invention relates to apparatus for obtaining a sample of molten metal from a flowing molten metal stream. Such apparatus is generally to be found in the U.S. Patent Office subclasses relating to measuring and testing, sampler and toller implements.
2. Description of the Prior Art
Apparatus in the prior art have generally been divided into two categories: Samplers that are designed to be immersed in molten material and apparatus that are designed to be inserted into a flowing stream of molten material. The problems encountered in designing sampling apparatus for use in each of the above two situations have generally been felt to be similar and for the most part they are. However, due to the fact that it is generally desirable to obtain a disc-like or flat sample along with a pintype sample the technology employed in designing an immersion-type sampler is not suitable in all respects for the design of a stream-type sampler.
In immersion-type samplers, mold chambers have been provided and, as described in U.S. Pat. No. 3,877,309, a venturi-type entry port, a pin sample tube and a flat sample mold cavity have also been employed. In the immersion sampler art it has been found to be desirable to reduce the resistance to flow of the molten metal entering the sample chambers thereby effecting smoother flow to form compact samples free of hollow areas.
In the stream sampler art, stream samplers such as those disclosed in U.S. Pat. No. 3,751,986 are formed having a substantially round transversely cross-sectioned disc-like cavity in association preferably with a pin-type sample appendage. An object of such prior art patent was the provision of a simplified and improved apparatus which provided adequate samples and which additionally provided means for housing the sampler in a versatile shipping container and which was further relatively inexpensive to manufacture and easy to use.
In the stream sampler art, however, problems have been encountered in equalizing the carbon content of the pin sample and disc-like sample. This problem is not so prevalent in the immersion sampler art. It can readily be appreciated though that substantial uniformity of carbon content in the sample is extremely important.
The stream and immersion sampler arts have also disclosed various attempts to provide sample containers made from molded sand. The use of such material has met with a degree of limited success, however, disadvantages are often encountered which have stemmed variously from the emission from the shell mold of objectionable substances associated with resin coated binders or the fact that the sand employed tended to provide a surface on the metal sample that was not smooth enough for testing purposes without preparation of the sample after its withdrawal from the mold cavity. A further difficulty encountered with core sand containers was that they were sometimes difficult to slide within their outer housings because of high friction between the sand and the housing.
It is also known in the art that in some applications it is desirable to vent the sample receiving cavity to the atmosphere. Problems also have been encountered in this regard since it has often been difficult to prevent the vent ports from undesirably filling with molten material thereby blocking escape of air from the inside of the chamber resulting in non-uniform samples. Various approaches have been taken to resolve this problem and the immersion sampler art and stream sampler art have approached solutions in somewhat different manners. This stems from the fact that the problem encountered in the two arts are at times somewhat divergent. Insofar as prior art venting methods are concerned it has also been found that the addition of an air permeable quantity of material in the vent port eliminated run out of material from the inside of the cavity. Of course, this adds to the cost of the unit and necessitates an additional manufacturing step.